It is a fine line. I would have to say that I'm pushing them too much. I had been going by the feeding schedule on the back of the bottles but a couple months ago I picked up a feeding schedule at the store that makes the nutes and started following them, which called for almost twice what I had been feeding them. And the problem has been getting worse so I would have to say too much nutes. I thought nute burn started at the top and worked down though, no?